Fluid sensing in a drip tray

ABSTRACT

A vacuum packaging appliance that detects the amount of liquid present while evacuating and sealing a container is disclosed. The appliance comprises a lid adapted to define a vacuum chamber when it is moved to a closed position relative to a trough in the base of the device. The trough in the lower portion of the device contains a heat-sealing element used to seal the contents of the bag once the vacuum packaging is complete. Disclosed are several embodiments relating to a liquid sensor molded into the walls of the trough. The liquid sensor comprises two electrodes that may be located on opposite sides of the trough or on the same side of the trough. When liquid is present in the trough, the capacitance and resistance between the electrodes changes, thereby sending a signal to a controller indicative of the amount of liquid within the trough while the container is being evacuated. The exact amount of liquid present is compared to a predetermined level of liquid. A vacuum pump controller may suspend operations if the amount of detected liquid exceeds a predetermined amount. The heat-sealing element is also controlled in accordance with the amount of liquid sensed in the trough. The amount of liquid sensed is also indicated to the operator.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Albritton et al.'s U.S. provisional application No. 60/492,046, filed Jul. 31, 2003, and entitled FLUID SENSING IN A DRIP TRAY, the contents of which are incorporated herein by reference. The present application is also related to Albritton et al's U.S. provisional application No. 60/491,876, filed Jul. 31, 2003, and entitled HEAT SEALING ELEMENT AND CONTROL OF SAME, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a vacuum packaging appliance for packaging products and more particularly to sensing liquid in a trough of the vacuum packaging appliance while evacuating a container and controlling a vacuum pump and heat sealing elements in accordance with the detected amount of liquid.

BACKGROUND OF THE INVENTION

Presently, various appliances and methods are used for the purpose of vacuum sealing plastic bags and containers to protect perishables, such as foodstuffs, and other products against oxidation. Conventional commercial appliances and some consumer appliances are generally expensive to manufacture, complex in construction and/or cumbersome to operate. There are many different types of these vacuum sealing appliances primarily used for commercial packaging purposes.

One type of conventional vacuum sealing appliance uses a vacuum nozzle that is inserted within a plastic bag for evacuation purposes. Although adaptable for low-volume home use, this type of appliance is cumbersome to use and normally requires a liquid separator or filter to prevent liquids or powders, retained within the bag, from being drawn into a vacuum pump connected to the nozzle.

Still another known vacuum sealing appliance places a portion of a bag, containing a product to be packaged, in a first vacuum chamber and extends an open end or neck of the bag into a second vacuum chamber. The first vacuum chamber is then evacuated to expand the neck of the bag to isolate the chambers from each other. Then a vacuum is drawn in the second vacuum chamber to evacuate the bag. Thus, isolation of the two chambers from each other, during evacuation of the second vacuum chamber, is dependent on the physical properties composing the neck of the bag (which is intended to form a static seal between the two chambers) and very close synchronization and calibration of the evacuation and sealing procedures and controls therefor. A vacuum sealing appliance of this type is disclosed in U.S. Pat. No. 3,928,938, for example.

A substantial problem with these and other prior art vacuum packaging appliances is that liquids evacuated from the bag contents collect in the vacuum chamber and may damage the vacuum pump itself. The presence of these unwanted liquids also causes failures in the heat sealing operations. For example, the temperature of the inner layer of a conventional vacuum sealable bag must be raised to approximately 130 degrees in order to melt the internal heat sealing layer of the bag. Energy supplied to the heat sealing elements is wasted on burning off these unwanted liquids, therefore the temperature of the inside layer of the bag does not reach the required level for heat sealing to occur.

Therefore, there exists a need for a vacuum packaging apparatus that is able to sense the presence and amount of liquid while evacuating a container. In addition to the sensing of liquid within the appliance, it would also be desirable to control operations of the vacuum pump itself and to further control the heat sealing operations in accordance with the amount of liquid sensed.

SUMMARY OF THE INVENTION

A vacuum packaging appliance that detects the amount of liquid present while evacuating and sealing a container is disclosed. The appliance comprises a lid adapted to define a vacuum chamber when it is moved to a closed position relative to a trough in the base of the device. A heat sealing element is used to seal the contents of the bag once the vacuum packaging is complete. Disclosed are several embodiments relating to a liquid sensor molded into the walls of the trough. The liquid sensor comprises two electrodes that may be located on opposite sides of the trough or on the same side of the trough.

When liquid is present in the trough, the capacitance and resistance between the electrodes changes, thereby sending a signal to a controller indicative of the amount of liquid within the trough while the container is being evacuated. The exact amount of liquid present is compared to a predetermined level of liquid. A vacuum pump controller may suspend operations if the amount of detected liquid exceeds a predetermined amount. The heat sealing element is also controlled in accordance with the amount of liquid sensed in the trough. The amount of liquid sensed is also indicated to the operator.

Other embodiments of the present invention include positioning the liquid sensing electrodes on opposite sides of the trough, on the same side of the trough, and on the top of the trough. The liquid sensors are also capable of providing a binary signal indicating the amount of liquid is above a predetermined level or an analog signal indicating the exact amount of liquid detected. The liquid sensing electrodes are molded into the trough walls to avoid direct contact with any liquid in order to avoid corrosion.

The present invention also includes a plurality of methods for controlling a vacuum packaging appliance for evacuating a container. These methods include controlling both the vacuum pump to obtain a desired vacuum within a vacuum packaging receptacle and sensing an amount of liquid in the vacuum circuit trough. The methods further determine an actuation control signal for energizing the heat sealing element as a function of the sensed amount of liquid in the vacuum circuit trough, and suspending operations of the vacuum pump based on the amount of sensed liquid.

The present invention therefore protects the vacuum packaging appliance and also greatly enhances the heat sealing operations of vacuum packaging appliances based on the detected amount of liquid which minimizes the amount of wasted bag material due to faulty sealing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of one embodiment of the vacuum packaging apparatus of the invention with the lid in a closed position.

FIG. 2 is an isometric view of the underside of the apparatus shown in FIG. 1.

FIG. 3 is an expanded isometric view of the control panel of the apparatus shown in FIG. 1.

FIG. 4 is an isometric view of the apparatus shown in FIG. 1 with the lid in an open position.

FIG. 5 is a view of the apparatus shown in FIG. 1 with the lid in a closed position showing the trough and the liquid sensors.

FIG. 6 is an isometric view of the trough removed from the apparatus.

FIG. 7 is transverse cross-sectional view of the device shown in FIG. 1.

FIG. 8 shows another embodiment of the liquid sensors mounted in a trough.

FIG. 9 is schematic diagram of the control circuitry of the heat sealing element in conjunction with the liquid sensing electrodes.

FIG. 10 is a flowchart showing a method of the present invention.

FIG. 11 is a flowchart showing another method of the present invention.

FIG. 12 is a flowchart showing a third method of the present invention.

FIG. 13 illustrates an isometric view of a trough structure according to another embodiment of the present invention.

FIG. 14A illustrates an isometric view of another trough structure according to the present invention.

FIG. 14B illustrates a top view of the trough structure of FIG. 14A.

FIG. 15 illustrates a top view of a trough having a mechanical liquid level apparatus, according to yet another embodiment of the present invention.

DETAILED DESCRIPTION

For clarity of presentation, the FIGS. are grouped and discussed as follows. FIGS. 1-4 describe general features and structures of the present invention relating to a vacuum packaging appliance. FIGS. 5-9 focus on the liquid sensing and controlling structures of the appliance and their interaction with the structures described in FIGS. 1-4. FIGS. 10-12 show flowcharts of methods enacted by the present invention.

FIG. 1 shows a vacuum packaging appliance 100 for vacuum packaging articles in a container that includes a liquid sensing capability. The vacuum packaging appliance 100 has a lid 102 and a base 104 that are pivotally connected at a back side 106 of the appliance 100. However, in alternate embodiments the lid and base maybe connected in any other convenient manner or they may be independent parts.

The lid includes a blade handle 108 that is associated with a blade (not shown) on the inside of the lid 102 of the vacuum packaging appliance 100. The blade handle 108 is slideably engaged within a slot 110 that extends substantially the entire length of the vacuum packaging appliance 100. Although the embodiment shown in FIG. 1 includes a blade handle 108 and associated blade, in alternate embodiments the blade handle 108, blade, and slot 110 may have various other configurations, or may not be present at all. The blade would be used for cutting sections of flexible bag material.

FIG. 1 also shows that the base 104 of the vacuum packaging appliance 100 includes an aperture 112 that is covered by a door 114. The door 114 is slideably mounted in the interior of the base 104 and includes a protrusion 116 that allows a trough that contains liquid sensing electrodes, to be removed or placed into the appliance 100. In alternate embodiments, the door 114 may take any convenient form and may be mounted to the vacuum packaging appliance 100 in any convenient manner. The vacuum packaging appliance 100 also includes a control panel 118 that is coupled with the base 104 and extends above the lid 102. In alternate embodiments, the control panel may be located in any convenient location on the apparatus or may not be included.

FIG. 2 is an isometric view of the underside of the vacuum packaging appliance 100. FIG. 2 shows that the vacuum packaging appliance 100 includes an alternating current (AC) power cord 202 that is coupled with the base 104. This will supply power to the vacuum pump and heat sealing elements as described below. In alternate embodiments, the power cord 202 maybe coupled with any convenient part of the vacuum packaging appliance 100 or may not be present. In still further alternate embodiments, the device may be powered by any convenient source such as one or more batteries providing direct current (DC) or various other known energy transfer technologies.

Also shown in the embodiment of FIG. 2, the base 104 has a recess 204 for storage of the power cord 202. To partially retain the power cord in the recess 204, the base also includes cord retention flanges 206. Two of the chord retention flanges 206 are rotatably coupled with the base 104 of the vacuum packaging appliance 100 and one chord retention flange 206 is fixed relative to the base 104. The rotatable chord retention flanges 206 allow a user to more easily store the power chord in the recess 204. However, in alternate embodiments any or all of the chord retention flanges 206 may all be fixed or rotatable or may not be present. In still further alternate embodiments, the recess 204 may take any convenient shape or may not be present.

FIG. 3 is a magnified view of the control panel shown in FIG. 1. The control panel 118 has a face plate 302 that is removably coupled with the base 104. The face plate 302 is removable to facilitate cleaning of the vacuum packaging appliance 100 and so that the apparatus 100 maybe manufactured with various face plates that can accommodate a greater or fewer number of openings for controls. Although the embodiment in FIG. 3 is shown with a removable faceplate 302, in alternate embodiments the faceplate 302 may be fixed or maybe integral with the base 104 or any other portion of the appliance 100.

The control panel 118 has rotary dial control 304, a cancel control 306, an instant seal control 308, a extended vacuum control 310, an accessory port 312 and an indicator lights 314. These indicator lights (green, yellow and red) provide feedback to the user indicative of the amount of liquid sensed in the appliance trough. However in alternate embodiments, various other controls maybe included in the control panel 118 and/or various controls maybe excluded from the control panel 118. The controls shown operate with a controller and liquid sensors as described below.

The rotary dial 304 has multiple positions that can control various aspects of the vacuum packaging appliance 100. For example, the rotary dial 304 has five positions: Accessory, 1, 2, 3 and Seal Only. However in alternate embodiments, the rotary dial may have more or fewer settings that can control various aspects of the vacuum packaging appliance 100. When the rotary dial 304 is in the accessory position, the accessory port 312 is activated and accessories (not shown) can be attached to the vacuum packaging appliance 100 either directly or via a vacuum hose (not shown). When the rotary dial 304 is in any position other than the accessory position, the accessory port 312 is sealed off and a vacuum is not drawn through the accessory port 312. Sealing off of the accessory port 312 can be accomplished by other convenient mechanism.

Positions 1, 2 and 3 allow the user to control the length of time the heat sealing element is active. Position 1 may activate the sealing mechanism for a first predetermined period producing a fragile or light seal. Position 2 may activate the sealing mechanism for a second predetermined period producing a medium heat seal, and position 3 may activate the sealing mechanism for a third predetermined period resulting in a heavy heat seal. Thus, the user can select the duration of the sealing process. For example sealing potato chips or fruit may require a light seal, whereas sealing meat would require a heavy seal.

The seal only position allows a user to use the apparatus to operate the sealing mechanism 420 (FIG. 4) only without requiring evacuation of the primary evacuation chamber 404 (FIG. 4). Although the apparatus shown in FIG. 3 includes a rotary dial 304 with five positions, in alternate embodiments the apparatus can include a rotary dial 304 that has more or fewer positions. For example a “smart seal” setting may be included. When the “smart seal” is selected the appliance automatically controls the current to the heat sealing elements in accordance with the actual element temperature.

After repetitive uses the heat sealing elements may become hot, therefore it requires less electrical power to heat the sealing elements to a sealing temperature. The control of the heat sealing elements is described below with reference to FIG. 9. In still further alternate embodiments, the apparatus may not include a rotary dial 304 or can include various buttons or other control mechanisms to control the various operations of the apparatus 100.

The control panel includes a cancel button 306. The cancel button 306 allows a user to cancel a vacuum operation or sealing operation at any time during the operation. In the embodiment shown in FIG. 3, the cancel button 306 is an electromechanical press-type switch. However, in alternate embodiments the cancel button 306 may be any type of user-activated control mechanism and/or the apparatus may not include a cancel button 306. FIG. 9 shows further details of the vacuum control structures.

The control panel 118 also includes an instant seal button 308. The instant seal button 308 allows a user to terminate the evacuation process and begin the sealing process at any time during operation of the vacuum packaging appliance 100. By way of example, a user may desire to only partially evacuate a container or not evacuate a container at all. Thus, the user may engage the container in the device and seal the container either without drawing a vacuum in the container or while drawing a vacuum in the container before the device begins automatically sealing the container.

In the embodiment shown in FIG. 3, the control panel 118 includes an accessory port 312. The accessory port allows a user to connect the apparatus to various containers as described in U.S. Pat. No. 4,491,310, by Hanns J. Kristen, issued Jul. 17, 1990, and assigned to the same assignee as this patent application, the complete contents of which is incorporated herein by reference.

An indicator light 314 serves to notify a user of the status of the vacuum packaging appliance 100. In the embodiment shown in FIG. 3, the indicator light is off when the device is inactive, solid green while the device is actively evacuating a container and emits intermittent green flashes when the device is sealing a container (not shown). However, in alternate embodiment the light may emit light of various colors and/or intensities and/or at various intervals to indicate various operations that the machine is performing. For example, the indicator light 314 may flash amber or some other color to indicate that the device is currently drawing an extended vacuum or the indicator light 314 may glow red to indicate that the accessory port 312 is active.

FIG. 4 is an isometric view of the apparatus 100 shown in FIG. 1 with the lid 102 in an open position. The lid 102 of the vacuum packaging appliance 100 includes two pneumatic latch chambers 402 and a primary evacuation chamber or vacuum circuit 408. Each of the pneumatic latch chambers 402 and the vacuum circuit 408 has flexible gaskets 406 at their perimeters. Additionally, the primary vacuum circuit or chamber 408 includes an evacuation port that is coupled to a vacuum pump or source housed inside the vacuum packaging appliance 100.

The lid also includes a sealing gasket 410, a cutting mechanism 412 that includes the handle and the blade (not shown) and a heat sealing element 433. The heat sealing element 433 touches electrical contacts 431 and 432 on the base of the device when the lid is closed. In this manner power is supplied to the heat sealing element via the contacts. This is desirable, as no power cord is necessary to run through the device hinges into the lid 102. This reduces the complexity of the device itself In alternate embodiments, the heat sealing element may be 2 wires or a wider element to ensure a proper heat seal. In other embodiments the heat sealing wires are located on the base of the appliance 100.

The base 104 of the vacuum packaging appliance 100 also includes an electromechanical switch 416, and evacuation apertures 418. In the embodiment shown in FIG. 4, the electro-mechanical switch 416 is positioned on the base such that when the lid 102 is in a closed position, the protrusion 414 is substantially vertically aligned with the electromechanical switch 416. Thus, when the lid 102 is in a closed position and then is further depressed, the protrusion 414 can actuate the electromechanical switch 416 and activate the vacuum packaging appliance 100.

The base 104 of the vacuum packaging appliance 100 has a recess 422 that is adapted to hold container material 424. The container material 424 is a roll of flattened, tubular container material and is supported on rotational supports 426. The rotation supports 426 are designed to engage the ends of the roll of container material 424 and rotate freely within the recess 422. Each rotation support 426 has grooves at its perimeter to facilitate rotation of the rotational support 426 and the roll of container material 424.

As shown in FIG. 4, the roll of container material is a single roll of continuously bonded plastic as described in U.S. Pat. No. RE34,929, by Hanns J. Kristen, issued May 9, 1995 a reissue patent based on U.S. Pat. No. 4,756,422, by Hanns J. Kristen, issued Jul. 12, 1988, assigned to the assignee of the present application, the complete contents of which is incorporated herein by reference. However, in alternate embodiments, the roll of container material 424 may be any convenient material.

The base 104 of the vacuum packaging appliance 100 further includes a groove 428 that is located in front of the trough 430. The groove 428 is positioned in the base 104 such that when the lid 102 is in a closed position, the cutting mechanism 412 is substantially vertically aligned with the groove 428. In operation, a user can move the handle 108 on the lid 102 within the slot 110 that will cause the cutting mechanism 412 to travel within the groove 428. If container material is present within the groove 428, the container material will be cut by the cutting mechanism 412. The cutting mechanism 412 is a safety cutting mechanism designed to reduce the risk of injury to a user.

The thermal sealing mechanism 433 includes one or more electrically conductive wires that produce heat when a voltage differential is applied across the length of the wire. In the embodiment shown, the electrically conductive wires are covered with a Teflon tape. However, in alternate embodiments, the wires maybe exposed or wrapped in a material. When the lid 102 is in a closed position, the sealing gasket 406 presses against the sealing mechanism 433. If the sealing mechanism 433 is activated and container material 424 is disposed between the sealing gasket 406 and the sealing mechanism 433, the container material 424 can be hermetically sealed.

Although the appliance 100 is described as including a sealing mechanism 433 that is integrated with the appliance, in alternate embodiments, the sealing mechanism 433 may be on the base of the device while the electrical contacts are located on the lid. Additionally in alternate embodiments, various other placements of the heat sealing mechanisms 433 may be employed in order to seal the container material 424.

In operation, when the lid 102 is in a closed position and is depressed such that the protrusion 414 actuates the electromechanical switch 416, the vacuum pump or source 434 is activated. In the embodiment shown in FIG. 4, the vacuum source first draws a vacuum in the latch chambers 402 via evacuation apertures 418. The evacuation of the latch chambers 402 draws the lid 102 down towards the base 104. Once the vacuum strength in the latch chambers 402 reaches a predetermined level, evacuation of the latch chambers 402 ceases and the vacuum source begins to evacuate the primary vacuum circuit or chamber 408 which is mated with the trough 430. Alternatively, after a predetermined time, vacuum to the primary evacuation chamber can be applied before vacuum is cut off to the latch chambers 402.

For cleaning purposes, the trough 430 is removable from the base 104 of the vacuum packaging appliance 100 through the door 114. In the embodiment shown in FIG. 4 the door 114 is manually slideable between and open and a closed position. However, in alternate embodiments, the door can be mechanically operated and/or can open in any convenient fashion. In still further alternate embodiments, the door 114 may not be present.

In operation, a user inserts an open end of a container, such as a flexible bag, into the trough 430 or attaches a container to the accessory port 312. The user then selects a setting on the rotary dial 304, closes the lid 102 and depresses the lid 102 past the closed position to actuate the electromechanical switch 416 with the protrusion 414. The vacuum pump or source will then evacuate the latch chambers 402 to hold the lid 102 relative to the base 104.

Once the lid 102 is secured relative to the base 104 by the latch chambers 402, the primary evacuation chamber 408 and the trough 430 are evacuated thus evacuating the open container inserted into the trough 430. When the vacuum strength reaches a predetermined level, the sealing mechanism will be activated to seal the container, if it is inserted into the trough 430. The evacuated and sealed container may then be released from the vacuum packaging appliance 100.

FIG. 5 shows a close-up view of trough 430 with the lid 102 in a closed position. Closing the lid 102 allows the evacuation of the container 504 to begin. FIG. 5 also shows a gasket 406, a protrusion 502, the heat sealing elements 420, and the liquid sensing electrodes 91A and 91B mounted in the trough 430. While the air is being evacuated from the container 504, all unwanted particles and liquids are contained in the bottom of the trough 430. This ensures that these unwanted substances do not damage the vacuum pump. The front side of the gasket 406 presses the container 504 into contact with the heating elements 420 and the protrusion 502.

The protrusion 502 helps to seal the evacuation chamber and trough 430 and also helps to keep the container 504 in position while the evacuation process is performed. Once the evacuation process is complete, the heat sealing elements 420 are activated. The front side of the gasket 406 maintains the container 504 in contact with the sealing elements 420 while the heat sealing process is performed. As described above, the container 504 has a heat sensitive layer that forms an airtight seal when activated by the elements 420. In this manner the container is evacuated and sealed.

FIG. 6 is an isometric view of the trough 430. In the embodiment shown, the trough 430 includes an extension that includes a protrusion 602 and one electrode 91A used as part of the liquid sensing mechanism. The protrusion 602 is designed to mate with the base of the appliance 100 in a snap-fit manner. The trough as shown in FIG. 6 also includes flanges 604 and a handle 606. Although the embodiment shown includes retention flanges 604, in alternate embodiments other convenient mechanisms may be used and or the trough 430 may not include a movement inhibiting mechanism.

FIG. 7 is a sectional view of the apparatus shown in FIG. 1, cut along the section line A-A. The embodiment shown in FIG. 7 shows the lid 102 in a closed position relative to the base 104. The base 104 includes the thermal sealing mechanism 420 that is positioned in substantial vertical alignment with the sealing gasket 406 in the lid 102 of the appliance. When the lid 102 is in a closed position related to the base 104, that the gasket 406 surrounding the vacuum circuit 408 and the trough 430 are in substantial vertical alignment and are in contact, thus defining an evacuation chamber.

The trough 430 is mounted in the recess 502 such that the flanges 604 of the trough 430 are positioned below the retention flanges 504 of the recess 502. Thus, vertical movement of the trough 430 with the recess 502 is substantially inhibited. The embodiment shown also shows that the base of the vacuum packaging appliance 100 includes a roll of container material 424 that is stored within the recess 422 within the appliance 100 and a vacuum pump 434.

The embodiment of FIG. 7 shows a heat sealing element 420 mounted adjacent to the top part of the trough 430. In operation, the element 420 receives electrical current from a power source or sources (not shown) which causes the element to heat up to temperatures exceeding 130 degrees thereby heat sealing the vacuum bag. The location of the heat sealing element 420 results in a seal that is close to the bag edge which results in the minimization of bag material necessary for packaging. Sensor 90 is a temperature sensor and is located adjacent to the sealing elements 420. Vacuum sensor 94 is mounted on the lid 102 of the device and detects the amount of vacuum within the vacuum circuit and trough 430. Electrodes 91A and 91B form a liquid sensor that senses the amount and presence of liquid in the trough 430.

In this embodiment, the electrodes 91A and 91B are molded into the sides of the plastic trough 430. A material such as aluminum may be used for these electrodes. These liquid sensors feed signals back to a controller as shown in FIG. 9. By providing one electrode molded into each side of the trough, a capacitive effect between the two electrodes is obtained. When liquid becomes present in the trough during the evacuation process it collects between the two electrodes 91A and 91B. The amount and presence of liquid now in the trough 430, acts as a dielectric material, which effects the capacitance between electrodes 91A and 91B. This change in capacitance may be monitored and determined by a controller 92 as shown in FIG. 9.

The controller 92 uses the signals to determine if a predetermined amount of liquid is in the trough and may adjust the amount of current supplied to the heat sealing elements in accordance with the detected amount of liquid. One feature of this embodiment is that the actual amount of liquid may be sensed. The signal produced by the electrodes 91A and 91B is analog in nature, so the exact level of liquid within the trough may be detected. Other embodiments of the invention include producing a binary signal that indicates that the amount of liquid is above or below a predetermined level. As will be described below, the heat sealing element controller 92 uses the information from the liquid sensor to modify the operator selected type of heat seal and to notify the operator of the sensed level of liquid in the appliance.

FIG. 8 shows another embodiment of the liquid sensing electrodes as seen from above the trough 430. In this embodiment the electrodes 91A and 91B are molded into the same side of the trough 430. In other embodiments the electrodes may be placed on the inside wall of the trough itself. The presence of liquid in the trough will change the resistance between the electrodes 91A and 91B. As shown in FIG. 9, these signals are fed back to a controller 92 that interprets the amount of liquid present in the trough. The signals produced from the electrodes are analog in nature, which allow exact indications of the amount of liquid present. Again, this type of liquid sensing used in conjunction with a controller may produce signals indicating the exact amount of detected liquid or the presence or absence of liquid in the trough 430. Although shown in the walls of the trough in FIG. 8, another embodiment of the invention place the electrodes on top of the trough 430.

A schematic diagram of the control circuitry of the heat sealing element in conjunction with the liquid sensing electrodes is shown in FIG. 9. FIG. 9 shows heat sealing elements 420, a temperature sensor 90, liquid sensor electrodes 91A and 91B, a heat sealing element controller 92, a vacuum pump controller 93, a vacuum sensor 94, a vacuum source pump 434, and a control panel 118. Once the type of heat seal is selected using control panel 118, and after the bag has been fully evacuated, the heat seal control circuitry is actuated to perform the sealing. Current is supplied to the heat seal element from electrical contact as described herein with reference to FIG. 4.

The controller 92 may be an ASIC device, a programmable logic device PLD or conventional microprocessor chip that contains the necessary software and logic means to control the operation of the heat sealing process. This further includes storing various times dependent on the type of heat seal selected by the operator. For example a heavy seal may be for a duration of 5 seconds while a light seal may energize the sealing elements 420 for one second. The controller 92 also includes timing circuitry designed to actuate and control the temperature of the sealing element based on the current used. For example, if multiple heavy seals are performed in a predetermined time period, the controller instigates a wait period in which the heat sealing element is allowed to cool. This prevents heat sealing element overheating which results in damaging of the vacuum containers and wasted materials. Patent application Ser. No. 60/491,876, entitled “Heat Sealing Element and Control of Same”, by inventors Charles Wade Albritton and Landon Higer, filed Jul. 31, 2003, is also incorporated by reference to show further details of the controller 92.

As mentioned above, problems with overheating and faulty sealing result from inaccurate temperatures of the heat sealing elements 420. The liquid sensor electrodes 91A and 91B allow the controller 92 to supply more or less electrical power to the elements based on this detected level of liquid in the trough 430. For example a standard heavy seal would be to supply a control signal current to the elements for 5 seconds creating a vacuum bag temperature of 130 degrees (required to melt the interior heat sealing layer). If the sensors indicate a high liquid content, a heavy seal may be produced by increasing the control signal current for a total duration of 6 seconds. If a low level of liquid is sensed, the control signal that actuates the sealing elements will not be modified by the controller 92.

The controller also sends a signal to the control panel 118 that contains indicators to alert the operator as to the level of liquid detected. For example a green light would indicate a low level of liquid, a yellow light would indicate a medium level of liquid, and a red light would indicate a high level of liquid. The controller may also shut down appliance operations if the level of liquid is above a predetermined level. In this manner the controller 92 monitors the presence and amount of liquid and is able to modify the control signals to the heat sealing elements and indicate this information to the operator.

FIG. 9 also shows the connection of the liquid sensing elements to a vacuum pump controller 93 that controls the vacuum pump 434. The vacuum pump controller 93 may be an ASIC device, a programmable logic device PLD or conventional microprocessor chip that contains the necessary software and logic means to control the operation of the vacuum pump and receive the inputs from the liquid sensors and the control panel 118. For example, the vacuum pump controller stores data relating to a safe level of liquid detected in the trough and also data relating to the required level of vacuum within the vacuum chamber. The connection of the vacuum pump controller to the various switches and sensors allows the vacuum pump to be shut down to avoid damage. In addition to the vacuum pump controller 93 deactivating the pump in response to detected levels of liquid, the vacuum pump 434 may also be deactivated in accordance with the sensed vacuum level within the vacuum circuit.

Vacuum sensor 94 sends a signal back to the controller 93 indicative of the amount of vacuum in the vacuum circuit and trough. Once the controller determines that a proper vacuum is obtained, the vacuum pump may be shut down. The vacuum pump 434 may also be enabled or disabled in response to a user activated switch on the control panel 118. The vacuum pump controller also controls the pump 434 in accordance with the other setting as found on control panel 118 and as described with reference to FIG. 3 above. The process the vacuum pump controller enacts is also shown and described with reference to FIG. 12.

FIG. 10 shows a method 1000 of controlling the vacuum packaging device as would be performed by the heat sealing element controller 92. In step S1002 the process begins when the operator couples the storage receptacle to the vacuum circuit by placing the container into the vacuum packaging appliance. In step S1004, the vacuum circuit is closed when the operator closes the lid of the device. In step S1006 the type of heat seal is determined. As is described below and as shown in FIG. 11, this step may contain inputs from a variety of parameters in order to determine the exact nature of the control signal applied to the heat sealing elements. For example the type of heat seal selected by the operator, the amount of liquid sensed in the trough, and the temperature of the heat sealing elements. In step S1008 the container is evacuated and is ready for sealing. In step S1010 the heat sealing element is actuated according to the determined control signal. In step S1012 feedback of the heat sealing process is provided to the user. For example lights on the control panel may indicate that sealing is being performed and/or that the heat sealing process is complete.

Also as described above the step of providing feedback to the operator includes controlling the lights on the control panel to display to the operator the exact amount of sensed liquid. As shown in FIG. 9, the heat sealing controller determines and actuates the current provided to the heat sealing element. As described above, the heat sealing process is controlled by the controller 92 in accordance with the inputs from multiple sensors and internal logic and programming.

FIG. 11 shows in more detail how the control signal is determined in step S1010 above. This process performed by the controller 92 begins in step S1102 by monitoring the presence and amount of liquid in the trough during the evacuation process in step S1008. The liquid sensing electrodes as shown in FIGS. 7 and 8 provide this information to the controller circuit 92. In step S1104 it is determined by the controller if a predetermined threshold of liquid has been exceeded. If the liquid is below a certain level, step S1108 is enacted and the time of the control signal to the heat sealing elements is set to a normal period (as set by the operator). If it has been determined in step S1104 that a predetermined amount of liquid is present, step S1106 adjusts the set time of the control signal to the elements to be high.

By incorporating the liquid sensing electrodes into the trough of the appliance, the heat seal may be controlled in a more precise manner, thereby resulting in less bag waste. This is a substantial improvement over prior art devices that are incapable of monitoring and adjusting the heat sealing process in accordance with the amount of liquid detected during the evacuation process. Other embodiments of the present invention include controlling the heat sealing elements in accordance with a plurality of input parameters such as, for example, the type of heat seal selected by the operator, the amount of liquid sensed in the trough, and the temperature of the heat sealing elements.

FIG. 12 shows a flowchart of the process 1200 by which the vacuum pump controller 93 controls the operation of the vacuum pump. The flowchart begins with step S1202 wherein the vacuum packaging receptacle containing food to be sealed is coupled to the vacuum circuit by being physically placed into the appliance. In step S1204 the user closes the lid of the appliance thereby closing the vacuum circuit. The vacuum pump is then activated in step S1206. Once the vacuum pump is operating and evacuation of the receptacle begins, the liquid sensors will begin to monitor the fluid level in the trough. In order to protect the vacuum pump from being damaged, in step S1208 it is detected if the fluid level has exceeded a predetermined safety level. If this predetermined level has been exceeded the vacuum pump is deactivated in step S1214. As an enhancement, liquid level feedback can be provided during evacuation. For example, a green LED could indicate a safe liquid level, and red LED could blink to indicate an unsafe level.

As will be appreciated, the activation of the pump can be initiated manually or automatically upon closure of the lid. The operation may also be enhanced by preventing activation of the pump when the liquid level is initially at a potentially unsafe level.

As long as the level of detected liquid is below the safety level, the vacuum pump can remain on. In step S1210 it is determined if the required level of vacuum (vacuum end point) has been reached. If this is the case the vacuum controller will then deactivate the pump in step S1214. If the vacuum end point has not been reached, the vacuum pump can remain on. It is also determined in step S1216 if the user has operated a switch on the control panel to deactivate the vacuum pump. If this is the case, the vacuum pump is shut of in step S1214. If the user has not indicated that the vacuum process be stopped then the controller will continue to operate the vacuum pump. The process described with reference to FIG. 12 ensures that the vacuum pump may be deactivated by the vacuum pump controller 93 for safety purposes for a plurality of reasons and conditions as detected.

The sensed liquid level information can also be incorporated into the evacuation and heat seal processes. For example, when high levels of liquid are present, the evacuation could be performed at a slower pace and the heat seal performed at a higher energization level.

FIG. 13 illustrates an isometric view of a trough structure 700 suitable for use with a vacuum packaging appliance in accordance with another embodiment of the present invention. The trough structure 700 includes a shallow pool structure 702 formed near an upper surface of the trough structure 700. The shallow pool structure includes a liquid sensor 704 formed therein. As liquid is evacuated from a bag 706, a liquid level 708 may increase to reach the shallow pool structure 702. At that point, the liquid can be sensed and the vacuum packaging appliance controlled accordingly.

FIG. 14A illustrates an isometric view and FIG. 14B illustrates a top view of another trough structure 720 suitable for use with a vacuum packaging appliance in accordance still another embodiment of the present invention. The trough structure 720 includes a dead zone structure 722 having a liquid sensor 724. As liquid is captured in the trough structure 720, the dead zone structure 722 liquid level rises accordingly and the liquid sensor 724 can sense the liquid level and this information used to control the vacuum packaging appliance as desired.

FIG. 15 illustrates a top view of a trough 800 and a mechanical liquid sensing apparatus 802 in accordance with another embodiment of the present invention. The mechanical liquid sensing apparatus 802 is responsive to a liquid level in the trough 800 to prevent fouling of a vacuum circuit and damage to a vacuum pump. The mechanical liquid sensing apparatus 802 includes a bobbing stopper 804 with locking pins 806, an arm 808 movably coupled with the stopper 804, a lever arm 810, and a plunger 812. The plunger 812 is arranged over an intake 814 of the vacuum circuit, and is coupled to a wall 815 of the trough 800 via a compression device 816. The lever arm 810 is mounted on a hinge 818 and coupled to the wall 815 via a compression device 820 and a tension device 822. As the water level in the trough 800 rises, the bobbing stopper 804 engages the arm 808 adjacent to the plunger 812. Eventually, as the liquid level rises sufficient to actuate the arm 810 to close the intake 814 with the plunger 812, thereby preventing liquid from entering the vacuum circuit. When the liquid level recedes, the tension device 822 actuates the arm 810, which in turn forces the bobbing stopper 804 back out into the trough, and the plunger 812 moves away from the intake 814 so that evacuation of gas can continue.

It will be understood by those skilled in the art that the above-presented description is provided by way of example only and is not intended to be limiting in anyway. Those skilled in the art will readily understand that numerous other embodiments of the invention are contemplated and possible which meet the scope and spirit of the invention. 

1. A vacuum packaging appliance for evacuating a container comprising: a base defining an upper support surface adapted to receive an open end of a container; a lid operatively associated with said base, said lid and said base defining a vacuum circuit therebetween to receive said open end of said container; at least one gasket surrounding said vacuum circuit for directly engaging said container such that said open end of said container is operatively associated with said vacuum circuit; a vacuum pump operatively associated with said vacuum circuit for selectively evacuating said vacuum circuit and said operatively associated container; a trough coupled to the base for receiving the open end of a container and collecting contents taken from the container while evacuating said container, and a liquid sensor mounted on the trough in order to sense liquid in the trough while evacuating the container.
 2. The vacuum packaging appliance of claim 1 wherein said liquid sensor is comprised of two electrodes molded into the walls of the trough.
 3. The vacuum packaging appliance of claim 2 wherein the two electrodes are molded into walls on opposite sides of the trough.
 4. The vacuum packaging appliance of claim 2 wherein the two electrodes are both molded into one wall of the trough.
 5. The vacuum packaging appliance of claim 2 wherein the two electrodes are mounted on top of the trough.
 6. The vacuum packaging appliance of claim 3 wherein the presence of liquid in the trough changes the capacitance between the two electrodes.
 7. The vacuum packaging appliance of claim 3 further comprising providing feedback to an operator related to the liquid level.
 8. The vacuum packaging appliance of claim 1 further comprising a heat sealing element arranged to seal an open end of said operatively associated container.
 9. The vacuum packaging appliance of claim 8 further comprising a heat sealing element controller operable to actuate said heat sealing element, and wherein said heat sealing element controller is responsive to the liquid sensor such that the heat sealing element is energized as a function of the liquid level.
 10. The vacuum packaging appliance of claim 9 wherein said liquid sensor sends an analog signal back to said heat sealing element controller indicative of the exact amount of liquid sensed in the trough.
 11. The vacuum packaging appliance of claim 9 wherein said liquid sensor sends a digital signal back to said heat sealing element controller indicating that amount of liquid sensed in the trough has exceeded a predetermined level.
 12. A method for controlling a vacuum packaging appliance, said vacuum packaging appliance including a heat sealing element, a vacuum circuit including a trough, and a vacuum pump, said vacuum pump operable to evacuate gas from said vacuum circuit, said heat sealing element operable to heat seal a vacuum packaging receptacle, said method comprising: coupling said vacuum packaging receptacle to said vacuum circuit; hermetically separating said vacuum circuit from ambient; operating said vacuum pump to obtain a desired vacuum within said vacuum packaging receptacle; sensing an amount of liquid in the vacuum circuit trough; determining an actuation control signal for energizing said heat sealing element as a function of the sensed amount of liquid in the vacuum circuit trough; and applying said actuation control signal to said heat sealing element.
 13. A method for controlling a vacuum packaging appliance as recited in claim 12, further including the act of providing two electrodes molded into walls of the vacuum circuit trough to sense the amount of liquid in the vacuum circuit trough.
 14. A method for controlling a vacuum packaging appliance as recited in claim 13, wherein a capacitance between said two electrodes changes as a function of the amount of liquid in the vacuum circuit trough.
 15. A method for controlling a vacuum packaging appliance as recited in claim 13, wherein the vacuum packaging appliance may be shut off when the amount of sensed liquid exceeds a predetermined level.
 16. A method for controlling a vacuum packaging appliance as recited in claim 14, wherein a signal indicating the exact level of liquid is provided.
 17. A method for controlling a vacuum packaging appliance as recited in claim 14, wherein a binary signal indicating that the level of liquid is above or below a predetermined level is provided.
 18. A method for controlling a vacuum packaging appliance as recited in claim 12, wherein the actuation control signal is also determined in accordance with the detected temperature of the heat sealing elements.
 19. A method for controlling a vacuum packaging appliance as recited in claim 18, wherein the actuation control signal is also determined in accordance with a user input.
 20. A method for controlling a vacuum packaging appliance as recited in claim 17, wherein the actuation control signal is also determined by comparing the sensed amount of liquid in the vacuum circuit trough to a predetermined level of liquid.
 21. A method for controlling a vacuum packaging appliance as recited in claim 20, wherein feedback is provided to the user indicating a high, medium, or low amount of liquid in the vacuum circuit trough.
 22. A vacuum packaging appliance for evacuating a container comprising: a trough for receiving the open end of a container and collecting contents and liquids taken from the container while evacuating said container, a heat sealing element for sealing the evacuated container; a heat sealing controller that actuates the heat sealing elements and receives a selected type of heat seal from an operator; and a liquid sensor that sends a signal to the heat sealing controller indicative of the amount of liquid taken from the container while evacuating said container.
 23. The vacuum packaging appliance of claim 22 wherein said heat sealing controller controls the power supplied to the heat sealing elements based on both the operator selected type of seal and the amount of liquid sensed in the trough.
 24. The vacuum packaging appliance of claim 23 further comprising an indicator that indicates to an operator the amount of liquid sensed in the trough.
 25. The vacuum packaging appliance of claim 24 wherein the liquid sensor and temperature sensor are located in the trough.
 26. A method for controlling a vacuum packaging appliance, said vacuum packaging appliance including a heat sealing element, a vacuum circuit including a trough, and a vacuum pump, said vacuum pump operable to evacuate gas from said vacuum circuit, said heat sealing element operable to heat seal a vacuum packaging receptacle, said method comprising: coupling said vacuum packaging receptacle to said vacuum circuit; hermetically separating said vacuum circuit from ambient; operating said vacuum pump to obtain a desired vacuum within said vacuum packaging receptacle; sensing an amount of liquid in the vacuum circuit trough; comparing the sensed amount of liquid in the vacuum circuit trough to a predetermined level of liquid; indicating to an operator that the level of liquid has exceeded the predetermined level; and suspending operations of the vacuum packaging appliance when the level of sensed liquid has exceeded the predetermined level.
 27. A method for controlling a vacuum packaging appliance, said vacuum packaging appliance including a heat sealing element, a vacuum circuit including a trough, and a vacuum pump, said vacuum pump operable to evacuate gas from said vacuum circuit, said heat sealing element operable to heat seal a vacuum packaging receptacle, said method comprising: coupling said vacuum packaging receptacle to said vacuum circuit; hermetically separating said vacuum circuit from ambient; sensing an amount of liquid in the vacuum circuit trough; determining if said vacuum pump should be activated based on the sensed amount of liquid in the vacuum circuit trough.
 28. A method for controlling a vacuum packaging appliance as recited in claim 27, further including the act of providing two electrodes molded into walls of the vacuum circuit trough to sense the amount of liquid in the vacuum circuit trough.
 29. A method for controlling a vacuum packaging appliance as recited in claim 28, wherein a capacitance between said two electrodes changes as a function of the amount of liquid in the vacuum circuit trough.
 30. A method for controlling a vacuum packaging appliance as recited in claim 28, wherein the vacuum pump may be shut off when a predetermined amount of vacuum exists within the vacuum circuit.
 31. A method for controlling a vacuum packaging appliance as recited in claim 29, wherein a signal indicating the exact level of liquid is provided.
 32. A method for controlling a vacuum packaging appliance as recited in claim 29, wherein a binary signal indicating that the level of liquid is above or below a predetermined level is provided.
 33. A method for controlling a vacuum packaging appliance as recited in claim 27, wherein the user may deactivate the vacuum pump.
 34. A vacuum packaging appliance for evacuating a container comprising: a vacuum pump for evacuating a vacuum circuit and the container; a liquid sensor located in the vacuum circuit that detects liquid in the vacuum circuit while evacuating the container; a vacuum sensor for detecting the amount of vacuum in the vacuum circuit; a control panel containing a switch for activating and deactivating the vacuum pump; and a vacuum pump controller that controls the activation and deactivation of the vacuum pump, wherein the vacuum pump controller is operatively connected to the liquid sensor, the vacuum sensor and the control panel to control the activation of said vacuum pump.
 35. The vacuum packaging appliance of claim 34, wherein said liquid sensor is comprised of two electrodes molded into the walls of a trough arranged to capture liquids evacuated from the container.
 36. The vacuum packaging appliance of claim 35 wherein the two electrodes are molded into walls on opposite sides of the trough.
 37. The vacuum packaging appliance of claim 35, wherein the two electrodes are both molded into one wall of the trough.
 38. The vacuum packaging appliance of claim 37, wherein the two electrodes are mounted on top of the trough.
 39. The vacuum packaging appliance of claim 36, wherein the presence of liquid in the trough changes the capacitance between the two electrodes.
 40. The vacuum packaging appliance of claim 36, wherein the presence and amount of liquid in the trough is indicated to an operator.
 41. The vacuum packaging appliance of claim 34, wherein the vacuum pump controller deactivates the vacuum pump when the level of sensed liquid in the trough exceeds a predetermined amount.
 42. The vacuum packaging appliance of claim 34, wherein the vacuum pump controller deactivates the vacuum pump in response to a user input.
 43. The vacuum packaging appliance of claim 42, wherein said liquid sensor sends an analog signal back to said vacuum pump controller indicative of the exact amount of liquid sensed in the trough.
 44. The vacuum packaging appliance of claim 42, wherein said liquid sensor sends a digital signal back to said vacuum pump controller indicating that amount of liquid sensed in the trough has exceeded a predetermined level.
 45. The vacuum packaging appliance of claim 35, further comprising a trough being part of the vacuum circuit, the trough arranged to receive the container and to capture liquids evacuated from the container tending to prevent liquid from being pulled into and fouling the vacuum circuit and damaging the vacuum pump, the trough including a shallow pool structure located near an upper surface of the trough, the liquid sensor being disposed within the shallow pool structure.
 46. The vacuum packaging appliance of claim 35, further comprising a trough being part of the vacuum circuit, the trough arranged to receive the container and to capture liquids evacuated from the container tending to prevent liquid from being pulled into and fouling the vacuum circuit and damaging the vacuum pump, the trough including a dead zone structure, the liquid sensor being disposed within the dead zone structure.
 47. A vacuum packaging appliance for evacuating a container comprising: a vacuum pump; a vacuum circuit coupled to the vacuum pump whereby the vacuum pump is operable to evacuate the vacuum circuit; a trough coupled to the vacuum circuit via an intake, the trough arranged to receive the container and to capture liquids evacuated from the container tending to prevent liquid from being pulled into and fouling the vacuum circuit and damaging the vacuum pump, the trough and vacuum circuit arranged to evacuate the container; and a mechanical liquid sensor disposed within the trough, the mechanical liquid sensor operable to close the intake when necessary to prevent liquid within the trough being evacuated through the intake. 